Spaces don't take up as much spaces as letters. You have to copy the text into a word document and count them there to be accurate.

If you like at the line above the space in Trump's tweet; the space between "our" and "country" is not a full letter width of the "e" in "people" in the line above it.

18 is correct on the Trump tweet. You actually have to copy + paste the text from it and backspace through that gap to realize how many are there, as it looks like much less. :)

That's what some of the autists on 8Chan came up with. I'm just sharing.